1. Field of the Invention
The present invention relates to an electronic control unit assembling method, an electronic control unit, and a vehicle brake hydraulic pressure control apparatus.
2. Description of the Related Art
A vehicle brake hydraulic pressure control apparatus has a base body in which a brake fluid line is formed, a motor for operating a pump which sucks a brake fluid from a reservoir formed in the base body, a sensor for detecting the behavior of a vehicle body, an electromagnetic valve attached to the base body, and an electronic control unit for controlling an operation of the motor.
The electronic control unit of the vehicle brake hydraulic pressure control apparatus has a control board for controlling operations of the electromagnetic valve and the motor based on the behavior of the vehicle body detected by the sensor, and a housing in which the control board is accommodated.
A housing of a conventional electronic control unit is configured such that a first accommodation chamber in which electronic components such as an electromagnetic valve protruded from the base body are accommodated, and a second accommodation chamber in which the control board is accommodated are formed in the internal space of the housing, and that a partitioning portion for partitioning between the first accommodation chamber and the second accommodation chamber is provided in the housing (see, e.g., JP-A-2008-105535).
A conventional electronic control unit is configured such that a sensor board on which a sensor is mounted is accommodated in the second accommodation chamber of the housing, and that the sensor board is supported by the partitioning portion. With this configuration, it is unnecessary to accommodate the sensor and the electronic control unit separately from each other in a vehicle interior.
Further, one of conventional electronic control units is configured such that a sensor board and a control board are accommodated in the second accommodation chamber of the housing in a hierarchical state by putting the sensor board on which the sensor is mounted on a second-accommodation-chamber-side surface of the partitioning portion. With this configuration, it is unnecessary to accommodate the sensor and the electronic control unit in a vehicle interior separately from each other.
In the case of the conventional electronic control unit in which the sensor board is supported by the partitioning portion, as described above, the detection accuracy of the sensor may be degraded when low-frequency vibrations generated at a housing exterior portion and an electric component are transmitted to the sensor via the partitioning portion of the housing.
In the case of vibration-welding a cover to the housing, when vibrations generated at the welding are transmitted to the sensor via the partitioning portion of the housing, the detection accuracy of the sensor may be affected.
Further, in the above conventional electronic control unit, a first connection terminal of the electric component and a second connection terminal provided in the housing are protruded from the second-accommodation-chamber-side surface of the partitioning portion. The first and second connection terminals are electrically connected to each other by being resistance-welded to each other. A plurality of sets of the first and second connection terminals resistance-welded to each other are arranged around the sensor board. Accordingly, in the conventional electronic control unit, a welding space is secured by setting the distance between the sensor board and each connection terminal at a large value such that the resistance-welding can be performed by pinching each connection terminal with the tip end portions of a welding tool. Thus, the conventional electronic control unit has the problem of increasing the size of the housing.